The present invention relates to a non-volatile variable capacitive device including a resistive memory cell.
Resistive memory cells have generated significant interest recently. Many believe its use as a resistive random-access memory (RRAM) could be an excellent candidate for ultra-high density non-volatile information storage. A typical resistive memory cell has an insulator layer provided between a pair of electrodes and exhibits electrical pulse induced hysteretic resistance switching effects.
The resistance switching has been explained by the formation of conductive filaments inside the insulator due to Joule heating and electrochemical processes in binary oxides (e.g. NiO and TiO2) or redox processes for ionic conductors including oxides, chalcogenides and polymers. Resistance switching has also been explained by field assisted diffusion of ions in TiO2 and amorphous silicon (a-Si) films.
In the case of a-Si structures, voltage-induced diffusion of metal ions into the silicon leads to the formation of conductive filaments that reduce the resistance of the a-Si structure. These filaments remain after the biasing voltage is removed, thereby giving the device its non-volatile characteristic, and they can be removed by reverse flow of the ions back toward the metal electrode under the motive force of a reverse polarity applied voltage.
The non-volatile characteristics and its simple configuration enables the resistive memory cell to be implemented in a wide range of different applications.